Acquired (Adaptive) Immunity – Lecture Review

30 question-and-answer flashcards covering key concepts from the lecture on acquired (adaptive) immunity, including immune branches, cell types, antibodies, complement, memory, immunocompetence, herd immunity, and vaccination.

What are the two main branches of the immune system?

Innate immunity and acquired (adaptive) immunity.

How does innate immunity differ from acquired immunity in terms of specificity?

Innate immunity is non-specific, whereas acquired immunity targets specific pathogens.

Into which two major components is acquired immunity divided?

Humoral immunity and cell-mediated immunity.

Which lymphocyte type is central to humoral immunity?

B lymphocytes (B cells).

Which lymphocyte type drives cell-mediated immunity?

T lymphocytes (T cells).

What are antigens?

Cell-surface proteins or large polysaccharides that the immune system recognizes as foreign; they stimulate antibody production.

What key feature makes acquired immunity faster and stronger upon re-exposure to a pathogen?

Immunological memory.

What is another name for antibodies?

Immunoglobulins (Ig).

Which immunoglobulin class is most abundant and long-lasting in adaptive responses?

IgG.

Which immunoglobulin class is produced first during an initial infection?

IgM.

Which immunoglobulin class is primarily involved in allergic reactions?

IgE.

What effector cell type releases large quantities of antibodies?

Plasma cells (effector B cells).

What is formed when an antibody binds to its antigen?

An antigen-antibody complex.

List four possible effects of an antigen-antibody complex.

Agglutination, precipitation, lysis, and neutralization (plus activation of complement).

Approximately how many plasma proteins make up the complement system?

About 20.

What event triggers the classical complement cascade?

The antibody’s constant region binds to the C1 complement protein.

What are chemokines?

A type of cytokine that attracts white blood cells to the site of infection (chemotaxis).

Where are B lymphocytes produced and mature?

In the bone marrow.

Where are T lymphocytes produced and mature?

They mature in the thymus gland.

Name the three functional categories of T cells.

Helper T cells, cytotoxic T cells, and repressor (suppressor) T cells.

How do cytotoxic T cells destroy infected or cancerous cells?

By releasing perforins and other toxins that create pores and cause cell lysis.

Why are helper T cells essential to adaptive immunity?

They activate both B cells and other T cells; without them (e.g., in AIDS) adaptive immunity is severely impaired.

What is immunocompetency in lymphocytes?

The ability to distinguish self from non-self; self-reactive cells are eliminated during development.

Define herd immunity.

Protection of susceptible individuals when a large proportion of the population is immune to a pathogen.

How do vaccines promote herd immunity?

They safely expose people to antigens, inducing acquired immunity and reducing pathogen spread.

Which vaccine preservative was incorrectly linked to autism?

Thimerosal.

What reduction in U.S. incidence has vaccination achieved for smallpox?

100 % reduction (eradicated).

Which cells release histamine after complement activation to promote inflammation?

Basophils and mast cells.

Which phagocytic cells are heavily recruited by complement proteins?

Neutrophils and macrophages (along with dendritic cells).